We propose to further our activities in the systematic determination of in situ thermodynamic and kinetic properties of the mitochondrial electron carriers and to continue to define the component physical-chemical interactions at each site of energy transduction, working toward the construction of a molecular mechanism of energy conservation. We will explore the relationship of the properties of in situ mitochondrial component to those of the isolated components and complexes to determine the contribution of the membrane milieu to the properties and activity of the components. Recombination of components, individual and in combination with phospholipid bilayer systems form the basis of model structural determination. At a higher level of complexity, structural foundation for the ultimate study of the mitochondrion will come from the simpler natural systems such as the chromatophore and retinal systems. Studies of membrane phenomena in artificial and natural systems will be directed toward the determination of the interrelationships with electron transfer and the hydrogen carrying capabilities of the respiratory components and the role of the membrane composition and structure in governing anion and cation uptake, release and distribution on an intra and transmembrane basis.